The present invention describes improvements in the design and manufacture of large-area, 3Helium gas proportional counters.
Large-area, 3He gas proportional counters are critically important tools for detecting and monitoring the movement of special nuclear materials. While the demand for 3He gas counters continues to increase, the availability of the most critical component, 3He, is diminishing.
The disclosed engineering innovations and improvements to the design of existing 3Helium gas counters will significantly reduce the quantity of 3He used in the counters, and the innovations will improve the efficiency and reduce the cost of the counters. The design innovations can be modeled computationally to determine optimal configurations, and the invention can reach beyond the embodiments described herein.
The innovations of this invention will have a significant impact on verification capabilities by enabling the manufacture of more large-area neutron detectors at lower cost per detector. This invention can immediately reduce the rate of consumption of 3He gas by implementing innovative changes in the fundamental design of existing, conventional 3He gas proportional counters. The invention will alleviate the immediate crisis caused by the shortage of 3He gas.
The development of efficient and cost-effective neutron detectors is a critical need for non-proliferation verification applications, including the detection of special nuclear materials and efforts to monitor their movement. The most common reactions used for thermal neutron detection are 3He(n,p), 6Li(n,α) and 10B(n, α), however, for large area detection applications, as in, for example, radiation portal monitors, 3He gas proportional counters are the most widely used detectors.
3He gas counters are attractive because the neutron capture cross section of 3He, 5330 barns, is significantly higher than that of 6Li or 10B. In addition, 3He is an inert gas, and gas proportional counters manufactured using 3He do not represent a health hazard. In contrast, boron trifluoride, enriched to 96% 10B, is also widely used in gas proportional counters, however the BF3 gas is highly toxic.
The 3He gas proportional counter is considered the “gold standard” for thermal neutron detection.
The demand for large-area 3He gas proportional counters has increased significantly in recent years in view of the potential threat raised by terrorists acquiring and transporting nuclear materials for use in acts of terror. However, the supply of 3He is not adequate to meet this demand, and the current annual production rate cannot be increased to meet the demand, so it is widely recognized that there is a critical shortage of 3He that will only get worse if the annual rate of consumption is not reduced significantly.
In response to the 3He shortage, many research groups have initiated basic research projects with the objective of developing new neutron detection technologies based primarily on 6Li or 10B, that match, or even exceed, the efficiency of 3He gas proportional counters. Unfortunately, the time to technical maturity of even the most impressively successful basic research program is on the order of 5 to 10 years. The immediate need for reducing the demand for 3He will not be satisfied by the development of new technologies that will not be ready for commercialization for the next 5 to 10 years.